Today, metal castings such as inlays, crowns and bridges are in wide use in prosthetic restoration in dentistry. In dental treatment, such metal castings need to be fixed to teeth or other prosthetic appliances made of various materials and therefore a number of fixation methods therefor have been investigated. In particular, as a result of recent development of adhesive resins capable of adhering satisfactorily to teeth as well as to metals, the technique of effecting fixation using adhesives has attracted attention.
In the technology of adhesion fixation, the surface treatment of metal castings is important and is a decisive factor for the functional period of prosthetic appliances. Previously, the present inventors reported that provision of an electroplated tin coat on metal castings, which is to be followed by application of an adhesive onto the tin coat, is effective as such surface treatment (The Journal of the Japan Prosthodontic Society, volume 28, pages 1023-1033, 1984). However, further investigation has shown that said treatment is till unsatisfactory in respect to bond strength and long-term water resistance and, therefore, improvements are desired.